2nd Place: Hitting the mark: Precision pesticide applications for the control of aphids in California lettuce

Lettuce growers in California’s central coast produce 70% of leafy greens brought to market in the United States. Aphids (lettuce-currant aphid [Nasovonia ribisnigri] and others) are a major pest in this system and are usually controlled using insecticidal sprays. Recent detections of insecticides in ground and surface water in the Salinas valley region have placed some commonly used insecticides at risk of increased regulation. There is a need to find more efficient ways to use insecticidal products to address these regulatory concerns. Newly developed automated precision sprayers, which use plant-detection sensors to apply chemical sprays directly over individual lettuce plants, can decrease the amount of pesticide used per acre by up to 90% in comparison to a traditional broadcast spray while still applying the same amount per plant. We conducted two field experiments in commercial romaine lettuce fields to test this technology for the control of aphids in lettuce. We tested two aphid-targeted materials, an ACC inhibitor, spirotetramat (Movento®), and a neonicotinoid, thiamethoxam (Actara®), at three different application rates. Plots were sprayed twice with one of the six precision spray treatments (material + rate), a broadcast spray at label rate or left as untreated controls. We sampled heads prior to and at various time points after treatment and assessed aphid numbers using visual counts. Results from this experiment validate the use of the automated sprayers to apply insecticides for the control of aphid pests in lettuce, but there remain opportunities to develop best-use-practices for this technology.